Rich People Even Have Better Stress Than poor by Anna Matteo fromlearningenglish.voanews.com.
Labor Day from Kids Britannica.com. Reprinted with permission from Compton’s byBritannica, © 2017 by Encyclopædia Britannica, Inc.
From MOLECULES: A VERY SHORT INTRODUCTION by Phillip Ball. Copyright © 2001by Phillip Ball. Reprinted with permission of Oxford University Press.